Hi
Freebmd has his birth
Births September qtr 1919   
Semple  Douglas  mothers maiden name Amos  Chipping Sodbury  6a 368 
However, to find his marriage, you will need to search the full GRO index which is available at your nearest main library if you live in the UK.  It can also be searched online if you have an Ancestry subscription or at 
www.findmypast.com which is a paysite
Marriages for the late 1930's onwards are sparse on freebmd 
This is probably his parents marriage
Marriages December qtr 1918    
Walter Semple to Dorothy E  Amos  Chipping Sodbury  6a 553